The voice solution provides a way for the router to integrate into a Telecommunications and Internet Converged Services and Protocols for Advanced Networks (TISPAN)/IP multimedia subsystems (IMS) environment to provide voice over IP (VoIP) functionality. IMS is a flexible network architecture that allows providers to introduce multimedia services across both next-generation packet-switched and traditional circuit-switched networks. It uses open interfaces and functional components that can be assembled flexibly to support real-time interactive services and applications.
IMS provides a standards-based architecture that allows mobile carriers to migrate to next-generation networks that support applications that combine voice, video, and data functionality. The European Telecommunications Standards Institute (ETSI) created TISPAN to extend IMS support to fixed-line carriers. This extension is commonly called fixed mobile convergence (FMC). IMS/FMC allows subscribers to access any network (wireless or fixed) from any device (computer, PDA, or cell phone) and to move seamlessly from one network to another.
The router acting as a packet gateway provides much of the border gateway function (BGF), as shown in the ETSI-TISPAN architecture in Figure 10:
Figure 10: Routers Running JUNOS Software in the ETSI-TISPAN Architecture
Table 8title defines the terms and abbreviations used in this topic.
Table 8: Terms and Abbreviations
| Term | Description |
|---|---|
|
BGF |
Border gateway function. Resides in the transport layer and polices and enforces traffic flows based on instructions from the SPDF. The packet gateway provides the BGF functionality. |
|
Context |
An association between terminations. |
|
Gate |
Unidirectional flow of IP packets as directed by the PGC. Sometimes called a pinhole. |
|
Ia |
A profile of the interface between an SPDF (the PGC) and the BGF (packet gateway). |
|
I-BGF |
Interconnect-BGF. The BGF between two peering partners. The packet gateway in the router provides much of the I-BGF function. |
|
IMS |
IP multimedia subsystem. |
|
IPC |
The VPGs and the MultiServices PIC communicate by exchanging Inter-Process Communication (IPC) messages over a TCP connection; this is internal (intra-chassis) communication. |
|
PG |
Packet gateway. A virtual device on the router that provides media processing and control as directed by the PGC. |
|
PGC |
Packet gateway controller. An external device that provides signal processing and directs the behavior of the PG. The PGC provides the service policy decision function (SPDF) shown in Figure 10. |
|
PGCP |
Packet Gateway Control Protocol (PGCP). An H.248 v3 protocol with Juniper Networks extensions. It provides management and signaling between the PG and the PGC. |
|
pgcpd |
The packet gateway pgcpd process running in the Router Engine decodes H.248 messages that VPGs receive from the PGC and translates the H.248 messages to IPC messages. |
|
SPDF |
Service policy decision function. Controls the BGF. In the Juniper Networks voice solution, the PGC acts as the SPDF. |
|
Stream |
A bidirectional flow within a context. |
|
Termination |
A local source and sink of packets. |
|
Virtual packet gateways (VPGs) |
A VPG consists of a packet gateway configuration on the Routing Engine. VPGs are controlled by a PGC. A VPG receives instructions from the PGC and instructs the MultiServices PIC how to treat voice traffic. |
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